Field of the Invention
The present invention relates to a method of processing a silicon substrate and a method of manufacturing a substrate for a liquid ejection head using the processing method.
Description of the Related Art
A liquid ejection head is configured to eject a liquid from an ejection orifice to cause the liquid to land on an object, e.g., a recording medium, to thereby record, for example, an image onto the object. As an example of the liquid ejection head, there is given an ink jet recording head configured to perform recording by ejecting ink onto a recording medium, e.g., paper. The liquid ejection head generally includes a plurality of ejection orifices provided in an ejection orifice forming member so as to eject a liquid, a flow path communicating to each ejection orifice, and a substrate including at least energy generating elements configured to apply ejection energy to the liquid in the flow path (hereinafter referred to as “substrate for a liquid ejection head”). The ejection orifice forming member is provided on the substrate so that the flow path is formed between the ejection orifice forming member and the surface of the substrate. Further, a supply path for supplying the liquid to the flow path is provided in the substrate so as to penetrate therethrough. In general, as the substrate for a liquid ejection head, a silicon substrate formed of silicon is used.
The substrate for a liquid ejection head is a member for supporting the ejection orifice forming member and is required to have high strength from the viewpoint of reliability. As one of procedures for enhancing mechanical strength of the substrate, there is given a procedure involving forming a beam in the supply path. For example, in Japanese Patent Application Laid-Open No. 2010-142972, there is disclosed a method of manufacturing an ink jet recording head including a beam formed so as to connect opposed long sides of a supply path. In beam formation in the manufacturing method disclosed in Japanese Patent Application Laid-Open No. 2010-142972, first, a sacrificial layer to be isotropically etched with an alkaline solution is formed on one surface side of a silicon substrate, and then an etching mask layer is formed on the other surface side of the silicon substrate. After that, the silicon substrate is subjected to anisotropic etching with an alkaline solution, so that a beam is formed in the supply path.
Further, as a method of stably manufacturing a substrate to be used in a liquid ejection head with high production efficiency, there is given a method disclosed in Japanese Patent Application Laid-Open No. 2007-269016. In the method disclosed in Japanese Patent Application Laid-Open No. 2007-269016, a supply path is formed, for example, by forming a non-through hole in a silicon substrate by laser processing and then performing anisotropic etching. Specifically, first, an etching mask layer having an opening corresponding to a portion in which a supply path is to be formed is formed on one surface of a silicon substrate. Then, at least two rows of non-through holes along an alignment direction of an ejection orifice row are disposed in the opening. After that, crystal anisotropic etching is performed to the opening to form a supply path.